With the development of industrial society, a variety of structures have been constructed in a large amount, a demand to smooth a excellent function of synthetic resin with a coloration which protects them and is more concerned with its appearance is steadily increased. However, in order to prepare such a synthetic resin and facilitate its workability on the field, a large quantity of volatile organic materials should be necessarily utilized.
When preparing and utilizing the synthetic resin, the volatile materials used may destroy a natural environment, and harmful effects on a human body are increasing. Therefore, environment-friendly preparation technique capable of replacing this is urgently needed.
In checking an emulsion polymerization technique as a preparation example of such a synthetic resin, the following techniques are well known in the art: first, a technique of conducting an emulsion polymerization by nucleating an emulsifier swollen with monomer within a micelle; second, a technique of conducting a nucleation in an absorbed emulsifier layer; third, a technique of conducing a nucleation in an aqueous solution; and fourth, a technique of conducting a nucleation in a monomer.
The development using numerous emulsion polymerization techniques like this has actively been made, but an epoxy resin has a low solubility as an intermediate and thus it has a fundamental difficulty in using an emulsion polymerization. Furthermore, the epoxy resin has a greater problem in a curing reaction activation, a curing rate control, compatibility and the like at a normal temperature.
As a solution on the above problems, for example, Korean unexamined patent publication no. 10-2008-0078824 discloses a process for producing an epoxy silane oligomer wherein, during the reaction of epoxy resins and copolymerizable silanes in the presence of a catalyst, a water base containing an emulsifier is pre-hydrolyzed or pre-condensed and then reacted again with the epoxy. Korean unexamined patent publication no. 10-2009-0069419 discloses a process for preparing a water-soluble epoxy resin wherein the epoxy resin and polyethylene glycol are reacted to increase its solubility, thus making the water dispersability easy. Korean patent no. 10-0910983 discloses a method for coating the surface of metal by applying butyl acetate to an epoxy resin. Japanese patent no. 1974-0002066 discloses a process preparing epoxy resin emulsion curing agent which makes a surface crystallization easy in a high moisture environment. Swiss patent no. 1993-0021680 discloses a process for preparing a curing agent which makes compatibility with aqueous epoxy resin easy in a cement mortar.
The aqueous epoxy resin composition obtained from pre-hydrolysis and pre-condensation using polymer compounds which can react with epoxy and have a high solubility, without using epoxy alone, may still remain an organic solvent due to the manner of polymerizing it with organic solvent to extract a volatile material. Also, this may induce a high cost because an organic solvent is lost and the production procedure is complicated.
Further, measures concerning compatibility due to a gelling, an activation reaction and a catalyst of controlling a curing rate at low temperature are not sufficient. High boiling point solvents such as alcohols or ethyl or butyl acetates as an aqueous epoxy resin may cause a danger or hazard on a fire or human body and it includes an antifoaming agent or a leveling agent. Thus, when volatile materials are contained as an aqueous epoxy even in small amount, it is possible to weaken a cross-linkage with water. In the case of curing at normal temperature, the regular thickness is more than 0.2 mm. In the environment such as high moisture, it is difficult to obtain smooth curing properties. Additionally, the amount capable of containing water as an aqueous epoxy may be not sufficient to carry out the work.
Also, since the workability in an increase of viscosity which results from temperature reduction or long-term storage may be limited, the composition capable of adding water freely and then using it may be required. It is urgently necessary to develop the composition which may minimize an ill-smelling due to volatile organic materials and amine curing agents, and a disturbance due to ammonium gas occurred in the curing reaction.
On the other hand, the present inventors has disclosed Korean patent no. 10-093222 (mortar agent) and Korean patent no. 10-0925850 (coating agent) relating to an aqueous epoxy resin composition using epoxy. These patents suggest a process for using an aqueous epoxy resin composition by incorporating a coagulant in the epoxy resin and using only water and emulsifier. These patents also suggest that, for a mortar agent, a curing reaction rate of epoxy resin and a hydration reaction of cement in the cross-linkage induce loss of moisture due to an interaction. For a coating agent, swelling after emulsion polymerization leads to a shape with immobility, water and emulsifier are again used to weaken the viscosity, and the phased rate control in a curing reaction leads to a smooth curing property. However, for controlling a reaction rate at low temperature (0˜5° C.) and lowering the workability according to an increase of viscosity, there was a limitation in that a desired amount of water as an aqueous epoxy resin may be freely post-added and used in a site work. Further, in an aqueous epoxy curing composition, there was need to further minimize ammonia gas which results from a curing reaction by removing a bad smell of amine.